fix #M100 - mind flayer's psychic blast during prayer

From a bug report:  the invulnerability conferred
during the multi-turn delay for a successful prayer was not protecting
against damage inflicted by hostile mind flayer's "wave of mental energy".

doc/fixes34.4

@@ -129,6 +129,7 @@ when a monster grew into a higher form which had previously been genocided,
 hero could still see for brief period after being blinded by potion vapors
 avoid crash when thrown potion hits bars before a monster
 don't give messages about seeing things happen while asleep
+protect hero from mind flayer's remote mental blast during successful prayer
 
 
 Platform- and/or Interface-Specific Fixes

src/monmove.c

@@ -404,9 +404,9 @@ register struct monst *mtmp;
 		}
 		pline("A wave of psychic energy pours over you!");
 		if (mtmp->mpeaceful &&
-		    (!Conflict || resist(mtmp, RING_CLASS, 0, 0)))
+		    (!Conflict || resist(mtmp, RING_CLASS, 0, 0))) {
 			pline("It feels quite soothing.");
-		else {
+		} else if (!u.uinvulnerable) {
 			register boolean m_sen = sensemon(mtmp);
 
 			if (m_sen || (Blind_telepat && rn2(2)) || !rn2(10)) {